The long-term objective of this research is to explain the mechanism of Insulin Action in the human body in order to contribute towards improvement of clinical treatment of diabetes. The specific objectives of the proposed study are to elucidate the mechanism by which the hormone stimulates the receptor in the plasma membrane and thereby regulates activities of enzymes, such as phosphodiesterase. We plan to study the characteristics of the insulin receptor interaction and those of hormone-sensitive phosphodiesterase, and try to delineate the mechanism by which the insulin signal is transmitted from the receptor to the enzyme.